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digging continued and the difficulties developed, some estimated that this type of canal might cost a billion dollars; and yet it is a question whether a sea-level canal be at all possible. Engineering skill is unable, at this day, to foretell what might happen in the Culebra Cut, if an attempt were made to dredge a free, open channel from ocean to ocean.
The French Company had prognostications of the slides at Culebra while their work was in progress. The distance through the mountain is nine miles, and no one can know where and when a slide may happen and the exact area which may be so involved. It has been stated that one slide which has taken place may cover an area of 75 acres.
As the bottom of the channel at Culebra is now about 45 feet above sea-level, it will require the deepening of the channel (for these nine miles) to the additional depth of 85 feet, to afford passage for large ships from ocean to ocean, without locks; and the additional depth of nearly 45 feet from Gatun dam to the foot of the mountain. It is impossible now to know, whether this great depth through the mountain could be excavated with safety or not. The flood-waters of the Chagres would also have to be carried off by a separate outlet.
By experience, the present plan is a success, so long as the Gatun dam and locks serve their intended purpose. The sea-level plan is in the realm of doubt and uncertainty. In the distant ages, if funds are abundant, the top of the mountain on both sides of the canal might be removed and the needed depth in the channel be secured.
With the large amount already invested and almost all depending on foreign patronage, is the American nation willing to double or treble the present investment? This problem belongs to the future, and to the favorable turn of the wheel of fortune. The nation has gained one of its main purposes; it can at least, by the present plan, take its warships through from one ocean to the other in any emergency.
One of the most important features of the present plan is the Gatun dam, and the immense lake behind it. This body of water is said to cover an area of 164 square miles. We should remember that the canal runs substantially a north and south direction; the isthmus at this point extending from east to west rather than from north to south; hence the Spaniards called the Pacific the “South Sea."
With these points of the compass in view, the Gatun lake extends very largely to the west of the canal and far up into the mountains; the extreme width being 20 miles, The lake then must extend almost 10 miles beyond the canal zone. The length of the lake from Gatun to the foot of the mountain is about 23 miles ; at this last point the lake is but 500 feet wide, simply the width of the canal. The average width for 16 miles from Gatun is 1,000 feet, so vessels for this distance will be steaming through a wide channel with full navigation facilities.
The dam at the south end of Culebra, at Pedro Miguel, is only such as is required to stop the spilling of the canal water into the Pacific. Here one set of locks is placed. At the further distance, to the south, of one and one-half miles is the Miraflores dam and two sets of locks. This dam creates a lake one and one-half miles long, and mostly supplied with water from the small river Cocoli and the Rio Grande, and this operates the two sets of locks at Miraflores.
The Gatun dam was the one uncertain engineering feat of the enterprise. Some very able engineer3 doubted whether the substratum would support the dam, with 85 feet depth of water behind it; for bed-rock was 200 feet below the surface. Fortunately a high hill was located near the center of the line of the dam. The dam extends from high land on one side of the Chagres river to high lands on the opposite side, being of a total length of 7500 feet; this central hill becoming a part of the dam. The artificial barrier is at the base, almost one-half a mile wide; and is 105 feet high, above sealevel, extending about 20 feet above the water-level; is 100 feet wide at the top, and from 388 to 400 feet wide at the water-level, according to height of the water.
The spill-way was placed not in the artificial part of the dam, but was cut through the central hill. The floor of the spill-way is 10 feet above sea level and 285 feet wide. There is a concrete dam across the spill-way 69 feet high; on top of this is a system of iron gates to be opened to let off the surplus water. When the water in the lake is at normal height, it is claimed that the spill-way is capable of discharging 140,000 cubic feet of water in a second. This water is not to be lost, for it will operate a power plant to furnish electrical power for canal uses. The spill-way at Miraflores will be operated in a similar manner.
The canal begins in the Atlantic near Colon, in Limon Bay and extends at sea-level 7 miles to Gatun locks; and for this distance is 41 feet deep and 500 feet wide. It then, from the locks, extends southward through Gatun lake 23 miles to the foot of the mountain; then 9 miles through Culebra Cut to Pedro Mi. guel; through this cut, the bottom width is 300 feet. It then passes on through Miraflores Lake, 142 miles, to the last two sets of locks. Here the sea-level canal be gins and extends 8 miles (500 feet wide) into the Pacific. The canal is thus about 50 miles long, from end to end. A large part of the material for the erection of the Gatun dam was taken from the Culebra Cut.
CONSTRUCTION AND COST. The total excavations for the canal and auxiliary works amount to the grand total of 260,370,028 cubic yards of earth and rock. Included in this is about 30,000,000 cubic yards dug by the French, useful to the Americans, because the same was dug in the line of the present canal. There were dug by the French Company about 48,000,000 cubic yards, which were of no use to us because they were not within the canal boundaries.
The cost of the canal, to date, will aggregate the vast sum of $400,000,000. In this is included $50,000,000, purchase money, to the French Company and to Panama, for the unfinished canal and the right of way.
It has taken an army of men to carry forward this work; in 1914 there were employed on the canal 23,113 men; and on the railroad and canal combined the total of 26,277 men. Americans were mostly paid in gold, and the foreigners were paid in Panama silver, from choice.
The French work, in the "cut" was much narrower than the American channel, and at the crest was dug to a depth of 161 feet; as the extreme height of the mountain, above sea-level, was 400 to 500 feet, the Americans had to excavate on an average of 100 feet below the work of the French Company; and on the widened strips they were required to cut down from the top of the ridge the full depth of the virgin soil. These figures can only give the approximate depth of the cut at Culebra, because the mountain for the whole 9 miles is not of uniform height.
The bends at Culebra almost equal the number of miles in length in the cut; at these curves it was required that the channel be widened to keep large ships from striking the shore while rounding the curves. The time required for a vessel to pass through the canal will be from 10 to 12 hours. Navigation, for safety, will be mostly in the daytime; but if necessity requires night transit, the canal from Gatun to the Culebra Cut has been furnished with lighthouses. It might be taking too much risk to pass through the locks and Culebra after dark, at least, by ships of large dimensions.
There are three sets of twin locks at Gatun, one set at Pedro Miguel, and two sets at Miraflores; that is 12 locks in all. The height of each lock is practically one-third of the lift from sea-level to lake-level, or onethird of 85 feet. There are two locks on each level, so as to give transit to a vessel going up and one going down at the same time; also to give passage in case one lock should become disabled.
These locks are made 110 feet wide and 1,000 feet long to accommodate the largest known ships. They are fitted also with shut-off appliances or safety gates, to be used to stop the flow in case of accident to the regular lock gates.
The locks are filled through large tunnels built in the lock-sides, with laterals opening underneath the lock-floors. And the vessels will be towed through the